The invention in general relates to apparatus for measuring the average speed of a target vehicle. More particularly it relates to a hand-held electrical apparatus for determining from a fixed observation post the distance between two fixed points along a highway then measuring the average speed of one or more target vehicles passing between those two fixed points. An example of two such fixed points would be two telephone posts along a highway.
Devices for measuring the average speed of a vehicle moving along a roadway are widely used by police officers in determining if target vehicles are exceeding the legal speed limit. One such commonly used apparatus is the conventional police radar unit. Another such apparatus is described in U.S. Pat. No. 3,530,382. These devices have several disadvantages: both are relatively large and bulky and generally require mounting in a vehicle which increases the visibility of the operator and thus reduces the effectiveness as a law enforcement tool; both are relatively complex and expensive limiting their availability; the radar can be defeated by radar warning devices; the device of U.S. Pat. No. 3,530,382 must be used in a vehicle traveling relatively closely behind the target vehicle, further contributing to the reduction in effectiveness.
Other U.S. Pat. Nos. relating to speed detection devices are 3,506,809; 3,406,395; and 1,676,965. All of these patents involve relatively complex devices each having objectives different from the present invention.
Because the apparatus of the invention is hand held and relatively inexpensive, it will have many more uses than the previous art. As just one example, spectators at races will find it useful for measuring the speed of the vehicles participating in the race, if an official comparison run is made around the track beforehand.